Automated velcro feed and cut assembly for ultrasonic welding applications

ABSTRACT

A motorless Velcro tape feed and cut assembly acting as a slave unit which cooperates with the horn of an ultrasonic welding machine. When the horn is brought down to carry out a welding action, it then depresses the spring-biased operating block of the assembly, causing it to shift downwardly from its normally raised position above a base plate to a final position adjacent to the base plate, the block returning to its raised position when the horn is retracted. Anchored on the base plate and projecting thereabove is an anvil which telescopes within an open-ended anvil channel in the block, the length of the anvil being such that in the final position of the block its head is then in operative relation to the horn to effect welding of a Velcro component onto a fabric lying on the upper face of the block. Disposed within the block is a Velcro tape feed roller that is driven in response to block movement as the block returns to its raised position, the rotating roller then advancing the leading end of the tape through the eye of a cutting block into the anvil channel to occupy a position therein above the anvil head. When in the course of a welding machine cycle the horn is brought down to depress the block, this action causes the leading end of the tape to be severed to form a Velcro component that is then pressed by the anvil head against the fabric, the Velcro component then being welded to the fabric by the horn.

BACKGROUND OF INVENTION

1. Field of Invention

This invention relates generally to the ultrasonic welding of Velcrotape components to a fabric, and more particularly to a motorless Velcrotape feed and cut assembly which acts as a slave unit with respect to anultrasonic welding machine and cooperates with the reciprocating hornthereof, whereby the up and down movement of the horn causes theassembly to feed the leading end of a Velcro tape into an anvil channeland to sever this end from the tape to form a Velcro component that isthen welded to a fabric.

2. The Prior Art

It is known to use in place of buttons, zippers and other conventionaltypes of fasteners, releasable "Velcro" fasteners which serve to holdtogether fabric panels or other complementary pieces. A Velcro fasteneris constituted by a male or hook component created by a uniform array ofstiff hooks and a female or loop component whose surface is constitutedby a pile of tiny soft loops. When the male and female components arepressed together, the hooks become embedded in the loops and are heldthereby until the components are peeled apart.

Velcro fasteners are snug, jam proof and washable. The componentsthereof are available in tape form which can be cut to a desired size.The male hook component, usually fabricated of nylon, is woven in theform of raised loops which are heated to retain their shape, the loopsbeing then clipped to form the desired hooks. The loop or femalecomponent is also fabricated of nylon, use being made of a ground tapeinterwoven with a dense multiplicity of yarns to form a pile surfacethat is then napped to create a continuous mass of uncut loops designedto couple with the male hooks.

As disclosed in my prior U.S. Pat. No. 4,382,303, it is known to producegarments whose closures are constituted by Velcro fastener componentsthat are ultrasonically welded to fabric panels. Ultrasonic welding maybe used to weld together two or more pieces or sheets of thermoplasticmaterial. This is accomplished by interposing the sheets between a"sonotrode" horn and an anvil. The horn is excited into vibration at anultrasonic frequency and the ultrasonic energy is tranformed into heatwhich softens the thermoplastic sheets and causes them to fuse together.The amount of heat generated is controlled by the adjustable amplitudeof ultrasonic vibration.

While machines are known capable of dispensing or die cutting pieces ofVelcro tape in a predetermined size appropriate to a fastener for aparticular fabric application, it has not heretofore been possible toautomate the ultrasonic welding operation. Thus, in a typical weldingoperation such as that necessary to produce Velcro fasteners forgarments of the type disclosed in my above-identified patent, anoperator must manually place a Velcro component over a sheet of fabricmaterial at an appropriate position thereon, and then operate anultrasonic welding machine to weld the component to the sheet.

This hand operation is time consuming and subject to human error, as aconsequence of which the cost of producing garments having Velcrofasteners is relatively high. Where the garments are intended to be ofthe disposable type and make use of inexpensive non-woven fabrics, thecosts incurred by conventional ultrasonic welding operations for theVelcro fasteners raises the production cost of the garment to a levelapproaching a point that is not acceptable in disposables.

SUMMARY OF INVENTION

In view of the foregoing, the main object of this invention is toprovide a motorless Velcro tape feed and cut assembly adapted tocooperate with the horn of an ultrasonic welding machine whereby the upand down movement of the horn causes the assembly to feed the leadingend of a Velcro tape into an anvil channel and to cut this end from thetape and to form a Velcro component that is welded to a fabric.

More specifically, an object of this invention is to provide an assemblyof the above type in which the feed roller which advances the leadingend of the Velcro tape into the anvil channel is operated by a ratchetmechanism that is automatically actuated when the ultrasonic weldinghorn is retracted from the assembly.

A significant advantage of the invention is that it expedites high speedwelding of Velcro components to a fabric; for all an operator need do isto place the fabric on the assembly at a proper position thereon, andthen press a switch button which turns on the ultrasonic welding machineto cause its horn to move down to depress the spring-biased block of aVelcro tape feed and cut assembly, the horn then retracting to permitthe block to return to its raised position, in the course of which theleading end of a Velcro tape is severed from the tape to form a Velcrocomponent which is then welded to the fabric.

Also an object of the invention is to provide an assembly of the abovetype which operates efficiently and reliably, and which can bemanufactured at relatively low cost.

Briefly stated, these objects are accomplished in a motorless Velcrotape feed and cut assembly acting as a slave unit which cooperates withthe horn of an ultrasonic welding machine. When the horn is brought downto carry out a welding action, it then depresses the spring-biasedoperating block of the assembly, causing it to shift downwardly from itsnormally raised position above a base plate to a final position adjacentto the base plate, the block returning to its raised position when thehorn is retracted. Anchored on the base plate and projecting thereaboveis an anvil which telescopes within an open-ended anvil channel in theblock, the length of the anvil being such that in the final position ofthe block its head is then in operative relation to the horn to effectwelding of a Velcro component onto a fabric lying on the upper face ofthe block. Disposed within the block is a Velcro tape feed roller thatis driven in response to block movement as the block returns to itsraised position, the rotating roller then advancing the leading end ofthe tape through the eye of a cutting block into the anvil channel tooccupy a position therein above the anvil head. When in the course of awelding machine cycle the horn is brought down to depress the block,this action causes the leading end of the tape to be severed to form aVelcro component that is then pressed by the anvil head against thefabric, the Velcro component then being welded to the fabric by thehorn.

OUTLINE OF DRAWINGS

For a better understanding of the invention as well as other objects andfurther features thereof, reference is made to the following detaileddescription to be read in conjunction with the accompanying drawings,wherein:

FIG. 1 is a perspective view of a Velcro feed and cut assembly inaccordance with the invention which acts as a slave unit that cooperateswith the horn of a standard ultrasonic welding machine, the block of theassembly being cut away to expose the mechanism housed therein;

FIG. 2 is a top view of the base plate of the assembly;

FIG. 3 is an elevation view of the base plate;

FIG. 4 shows a fabric placed on the top face of the block of theassembly with the welding machine horn depressing the block to ahalf-way down position;

FIG. 5 schematically shows the relationship which exists when the blockis at its halfway down position;

FIG. 6 schematically shows the relationship which exists when the blockis at its final down position;

FIG. 7 illustrates, in perspective, the ratchet mechanism action whichtakes place when the horn of the machine proceeds to retract;

FIG. 8 schematically shows how, as a result of this ratchet mechanismaction, the feed roller causes the leading end of the tape to enter theanvil chamber;

FIG. 9 schematically shows the relationship which exists when the hornis fully retracted and the block is at its fully raised position; and

FIG. 10 shows the fabric with the Velcro component welded thereto.

DESCRIPTION OF INVENTION The Basic Structure

Referring now to FIGS. 1 and 2, there is shown a Velcro tape feed andcut assembly in accordance with the invention, generally designated byreference numeral 10. This assembly acts as a slave unit that cooperateswith a standard ultrasonic welding machine, generally designated bynumeral 11.

Welding machine 11 includes an ultrasonic generator 12 supported at araised position on a column 13 and an ultrasonic energy horn 14 mountedat the end of a hydraulic piston 15. An operator, by pressing a switchbutton, activates piston 15 to move horn 14 in the downward directionfrom its normally retracted position to a fully extended position, andto then return to its retracted position, thereby completing a weldingcycle.

Assembly 10 is constituted by a spring-biased operating block 16 whichis mounted above a stationary base plate 17 having the same rectangulardimensions. Anchored on base plate 17 are guide posts 18 and 19 whichare received in corresponding bores in the block. Behind guide posts 18and 19 are return springs 20 and 21 which are anchored on the base plateand are received in corresponding bores in the block. Thus, the blockand the base plate are maintained in parallel planes.

Also anchored on base plate 17 is an anvil 22 having a rectangular crosssection. Anvil 22 telescopes within an open ended anvil channel 23having a rectangular cross section corresponding to that of the anvil.

Housed within block 16 is a feed roller 24 mounted on an axle 25 whichextends through the block and terminates at either end in a ratchetwheel, only ratchet wheel 26 being shown in FIG. 1. A Velcro tape 27providing the desired Velcro component (male or female) is drawn from asupply reel (not shown) and fed into a slot 28 in the front side ofblock 16. The tape is engaged by the ribbed surface of roller 24 andpasses from the roller through the eye 29 of a cutting blade 30. Blade30 defines a wall of anvil channel 23, and its eye cooperates with theadjacent edge of the moving anvil therein to effect a shearing action.

Associated with each ratchet wheel is a spring-biased pawl 31 which soengages the teeth of the wheel as to prevent counterclockwise rotationthereof. Thus, ratchet wheel 26 is only capable of rotating in theclockwise direction to advance tape 27. Also engaging the teeth of theratchet wheels at either end of the roller axle are drive fingers 32 and33. These are pivotally mounted within notches on opposite ends of baseplate 17 and are spring-biased toward the teeth.

When spring-biased block 16 is depressed by horn 14, it then is shiftedfrom its normally raised position above base plate 17 (represented inFIG. 1 by plane RP coextensive with the underface of block 16) to itsfinal fully down position (represented in FIG. 1 by plane FP coextensivewith the upper face of base plate 17). In the course of this downwardmovement, drive fingers 32 and 33 are disengaged from the teeth of theirassociated ratchet wheels. But when horn 14 retracts to permitspring-biased block 16 to go up from its final down position FP to itsfully raised position RP, then the drive fingers engage the teeth tocause feed roller 24 to turn in the clockwise direction to advanceVelcro tape 27.

A sheet of fabric 34 to which a Velcro tape component is to be welded ata desired site thereon is placed on the top face of block 16 with thesite to be welded in registration with anvil channel 23. This fabric orsheet may be of any woven or non-woven type capable of beingultrasonically welded.

We shall now describe the successive operating phases of the unit.

Operating Phase I

As shown in FIGS. 4 and 5, when the operator actuates the ultrasonicwelding machine, horn 14 then proceeds to move down to engage anddepress block 16 of the assembly. In these figures, block 16 is shown atits halfway down position midway between the fully raised position RPand its final down position FP. In this halfway down position, theleading end 27L of tape 27 then lies within the anvil channel 23 on thehead of anvil 22, the leading end having been brought into the channelas a result of a previous upward movement of the horn and the block.

At this point, the eye 29 of the blade is in registration with the headof the anvil, and as the block moves further down, the blade shears thetape, using the anvil head as the cutting edge, to yield a Velcro tapecomponent.

Operating Phase II

When, as shown in FIG. 6, block 16 reaches its fully down position, thesevered leading end 27L of the Velcro tape then lies on the head ofanvil 22 under fabric 34. The fabric and the tape component aresandwiched between the anvil head and the ultrasonic horn and aresubjected to ultrasonic energy to effect welding of the component to thefabric.

Operating Phase III

The fully extended horn 14 holds block 16 at its final down position FPfor a brief period until the welding operation is completed, and it thenproceeds, as shown in FIGS. 7 and 8, to retract. As a result of thisretraction, spring-biased block 16 of the assembly then proceeds to moveupwardly toward its raised position RP. In the course of this upwardmovement, ratchet wheel 26 is turned by drive finger 32 in the clockwisedirection to cause feed roller 26 to advance a fresh leading end 27L oftape 27 into anvil channel 23 in readiness for the next operating cycleof the ultrasonic welding machine.

When horn 14 is fully retracted, as shown in FIG. 9, and block 16 isback to its fully raised position, one can then remove fabric 34 fromthe block. As shown separately in FIG. 10, fabric 34 now has a Velcrocomponent 27L welded thereon. One can now put another fabric on theblock and repeat the operating cycle to weld a Velcro component thereto.

Modifications

Instead of using a ratchet mechanism as shown in the figures to causeturning of the feed roller to advance the Velcro tape into the anvilchannel only when the block moves upwardly from its final down positionto its fully raised position, one can use a rack and pinion arrangementfor the same purpose. In this modification, the pinion is mounted on theaxle of the roller and engages a spring-biased rack pivotally mounted onthe base plate. Or a cam arrangement may be used responsive to themovement of the block relative to the base plate to turn the feedroller, as required.

Because in practice the thickness of the fabric and the thickness of theVelcro tape to be welded thereto depend on the nature of the garment andmay differ from job to job, in order to effectively compress the fabricand the tape piece between the ultrasonic energy horn and the head ofthe anvil, shims of different thickness may be used on the head of theanvil to provide the appropriate separation between the anvil head andthe horn.

Also, while there has been shown a unit for use with a single Velcrotape, in practice the unit may be designed to accommodate two or moretapes, in which case an anvil channel and an anvil are provided for eachof the tapes, as well as a cutting blade and a feed roller therefor.

While there has been shown and described a preferred embodiment of anautomated velcro feed and cut assembly for ultrasonic weldingapplications in accordance with the invention, it will be appreciatedthat many changes and modifications may be made therein without,however, departing from the essential spirit thereof.

I claim:
 1. A Velcro tape feed and cut assembly functioning as a slaveunit that cooperates with a standard ultrasonic welding machine providedwith a horn which is brought down to carry out a welding operation andthen retracted in the course of a machine cycle, the assemblycomprising:A a block spring-mounted above a stationary base plate anddepressible by the downwardly-moving horn from a raised position abovethe plate and parallel thereto to a final down position adjacent theplate; B a feed roller housed in the block and rotatable therein, saidroller when rotated in the clockwise direction acting to advance aVelcro tape; C an open-ended anvil channel formed in the block in thepath of tape advance to receive the leading end of the tape; D a cuttingblade adjoining the channel, said channel extending between the upperand lower faces of the block; E an anvil anchored on said base plate andprojecting into said channel whereby when the block is partiallydepressed by the horn, the head of the anvil lies against the blade toprovide a cutting edge therefor; and as the block is further depressed,the leading end of the tape which lies within the channel is severed,the severed end forming a Velcro component which is brought by the headinto contact with the underside of a fabric lying on the upper face ofthe block, the Velcro component and the fabric being sandwiched betweenthe anvil head and the horn to effect a welding action; and F meansresponsive to upward movement of the block while the horn is beingretracted to rotate said roller clockwise to advance the leading end ofthe tape into the channel.
 2. An assembly as set forth in claim 1,wherein said means is constituted by a ratchet wheel mounted on an axlesupporting the roller, and a drive finger pivotally mounted on the baseplate engaging the teeth of the wheel.
 3. An assembly as set forth inclaim 2, further including spring means to bias the drive finger towardsaid teeth.
 4. An assembly as set forth in claim 2, further including apawl engaging said teeth to prevent counterclockwise rotation of thewheel.
 5. An assembly as set forth in claim 1, further including guideposts anchored on the base plate and received in bores in said block tomaintain said block and said plate in parallel relation in the course ofblock movement.
 6. An assembly as set forth in claim 5, furtherincluding helical springs anchored on the base plate and received inbores in said block.
 7. An assembly as set forth in claim 1, whereinsaid blade has an eye through which said tape passes into the channel.